scholarly journals Minimization of CaF2 spherical surface deformation caused by annealing

2021 ◽  
Vol 60 (11) ◽  
Author(s):  
František Procháska ◽  
Matěj Machek ◽  
Jan Václavík ◽  
Vasyl Karabyn
Keyword(s):  
Surface Deformation ◽  
Spherical Surface

scholarly journals Deformation measurement by single spherical near-field intensity measurement for large reflector antenna

2021 ◽  
Vol 21 (10) ◽  
pp. 258
Author(s):  
Qian Ye ◽  
Bo-Yang Wang ◽  
Qiang Yao ◽  
Jin-Qing Wang ◽  
Qing-Hui Liu ◽  
...  
Keyword(s):  
Surface Deformation ◽  
Focal Point ◽  
Spherical Surface ◽  
Outer Space ◽  
Near Field ◽  
Elevation Angle ◽  
Physical Optics ◽  
Electric Intensity ◽  
Deformation Intensity ◽  
Main Reflector

Abstract This paper presents a new method to obtain the deformation distribution on the main reflector of an antenna only by measuring the electric intensity on a spherical surface with the focal point as the center of the sphere, regardless of phase. Combining the differential geometry theory with geometric optics method, this paper has derived a deformation-intensity equation to relate the surface deformation to the intensity distribution of a spherical near-field directly. Based on the finite difference method (FDM) and Gauss-Seidel iteration, deformation has been calculated from intensity simulated by geometrical optics (GO) and physical optics (PO) methods, respectively, with relatively small errors, which prove the effectiveness of the equation proposed in this paper. By means of this method, it is possible to measure the deformation only by scanning the electric intensity of a single hemispherical near-field whose area is only about 1/15 of the aperture. The measurement only needs a plane wave at any frequency as the incident wave, which means that both the signals from the outer space satellite and the far-field artificial beacon could be used as the sources. The scanning can be realized no matter what attitude and elevation angle the antenna is in because the size and angle of the hemisphere are changeable.

An Optoelectronic System for Real-Time Surface Deformation Measurements

Vestnik MEI ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 101-108
Author(s):  
Anton Yu. Poroykov ◽  
◽  
Konstantin M. Lapitskiy ◽  
Keyword(s):  
Real Time ◽  
Surface Deformation ◽  
Optoelectronic System ◽  
Deformation Measurements

Free-surface deformation measurement

1997 ◽  
Author(s):  
H. Stahl ◽  
Kevin Stultz ◽  
H. Stahl ◽  
Kevin Stultz
Keyword(s):  
Free Surface ◽  
Surface Deformation ◽  
Deformation Measurement ◽  
Free Surface Deformation

MEASURING COSEISMIC SURFACE DEFORMATION WITH DIFFERENTIAL TOPOGRAPHY IN UNDERGRADUATE GEOSCIENCE COURSES

2019 ◽  
Author(s):  
Chelsea Phipps Scott ◽  
◽  
J. Ramon Arrowsmith ◽  
Christopher J. Crosby
Keyword(s):  
Surface Deformation

scholarly journals Economical rapid-prototyping of aspherical lenses

2019 ◽  
Vol 215 ◽  
pp. 04001 ◽  
Author(s):  
Angelina Müller ◽  
Matthias C. Wapler ◽  
Ulrike Wallrabe
Keyword(s):  
Thermal Expansion ◽  
Rapid Prototyping ◽  
Shape Optimization ◽  
Surface Deformation ◽  
Fabrication Process ◽  
Aspherical Lens ◽  
Laser Structuring ◽  
Aspherical Lenses ◽  
Design Freedom ◽  
Micro Lens

We present a rapid-prototyping process to fabricate aspherical lens arrays based on surface deformation due to thermal expansion of PDMS. Using laser-structuring and molding in combination with an FEM-based shape optimization, we were able to design, fabricate and characterize different micro-lens arrays. This fabrication process can be used for almost any kind of arbitrary lens shape, which allows for a large design freedom for micro lenses.

scholarly journals Preliminary Research on a Comparison and Evaluation of FY-4A LMI and ADTD Data through a Moving Amplification Matching Algorithm

2020 ◽  
Vol 13 (1) ◽  
pp. 11
Author(s):  
Pengfei Li ◽  
Guofu Zhai ◽  
Wenjing Pang ◽  
Wen Hui ◽  
Wenjuan Zhang ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Spherical Surface ◽  
Operation Time ◽  
Mean Value ◽  
China Meteorological Administration ◽  
Matching Algorithm ◽  
Lightning Detection ◽  
Spatial Differences ◽  
System Data ◽  
Spatial Threshold

In this study, a new moving amplification matching algorithm was proposed, and then the temporal and spatial differences and correlation were analysed and evaluated by comparing the FengYun-4A Lightning Mapping Imager (FY-4A LMI) data and the China Meteorological Administration Lightning Detection Network Advanced TOA and Direction (CMA-LDN ADTD) system data of southwest China in July 2018. The results are as follows. Firstly, the new moving amplification matching algorithm could effectively reduce the number of invalid operations and save the operation time in comparison to the conventional ergodic algorithms. Secondly, LMI has less detection efficiency during the daytime, using ADTD as a reference. The lightning number detected by ADTD increased from 5:00 AM UTC (13:00 PM BJT, Beijing Time) and almost lasted for a whole day. Thirdly, the trends of lightning data change of LMI and ADTD were the same as the whole. The average daily lightning matching rate of the LMI in July was 63.23%. The average hourly lightning matching rate of the LMI in July was 75.08%. Lastly, the mean value of the spherical surface distance in the matched array was 35.49 km, and roughly 80% of the matched distance was within 57 km, indicating that the spatial threshold limit was relatively stable. The correlation between LMI lightning radiation intensity and ADTD lighting current intensity was low.

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